Browsing by Author "Aka, Cemal"

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Effect of Synthesis Conditions on the Size and Morphology of Magnetic Nickel Particles
(Wiley-v C H verlag Gmbh, 2025) Kivrak, Burak; Akyildiz, Hasan; Aka, Cemal; Akyol, Mustafa
This study compares the properties of nickel (Ni) particles synthesized through the chemical-reduction-reactions (CRRs) under open-atmosphere and pressurized (solvothermal) conditions. The primary objective was to produce Ni particles with sizes below 100 nm with smooth surfaces, single-phase composition, highly crystalline, mono-disperse, and magnetic which are essential for constructing nanostructured Ni suitable for diverse applications. CRRs were conducted in a glass beaker for ambient pressure synthesis and a solvothermal reactor for pressurized conditions. The structural, morphological, and magnetic characteristics of the samples were investigated in detail. The findings demonstrated that the manipulation of the synthesis conditions in both methods allowed the formation of Ni particles with a wide range of morphologies, crystallinity, and purity. Besides, particle sizes varied from nanometer to micrometer scale, depending on the synthesis approach and processing conditions. Moreover, the relation between magnetic characteristics and morphological features was discussed in detail. Therefore, this research provides a comparative evaluation of two different synthesis methods, offering insight into the optimization of conditions for producing phase-pure, magnetic, and equiaxed Ni nanoparticles (NPs). By addressing the challenge of achieving mono-disperse Ni NPs, this study contributes to the understanding of synthesis techniques and elucidating the mechanisms underlying the formation of magnetic Ni NPs.
Citation - WoS: 10
Citation - Scopus: 11
Phase (1t/2h) Dependent Electromagnetic Wave Absorbing Performance of Flower-Like Mos2 Nanosheets
(Elsevier, 2023) Aka, Cemal; Kıvrak, Burak; Teksen, Fikret Alpay; Akyıldız, Hasan; Akgöl, Oğuzhan; Karaaslan, Muharrem; Akyol, Mustafa
A study was carried out to determine the phase-dependent electromagnetic wave (EMW) absorption performance of MoS2 particles via systematically diversified hydrothermal synthesis conditions such as time, temperature, precursor molarity, and oxalic acid concentration. The formation of mixed-phase structure was verified depending on the presence of the characteristic diffraction peaks belong to 1T (trigonal, P3?m1 space group) and 2H (hexagonal, P63/mmc space group) phases in the X-ray diffraction (XRD) patterns. Phase-pure 2H-MoS2 was obtained at 200 degrees C after 12 h of reaction and using 5 mmol oxalic acid. Microscopic examinations indicate that MoS2 particles formed by assembling several nanosheets to create a flower-like morphology. The size, shape, and the distance between the nanosheets were observed to change with increasing temperature, time, and acid concentration. The band gap was found to be modified depending on the phase distribution and decreased from 1.54 eV (2H) to a minimum of 0.64 eV (1T/2H) with the formation of the 1T (metallic) phase. Finally, the minimum reflection loss was measured as -67.73 dB (99.9999 % of absorption at 9.05 GHz) with an effective absorption bandwidth (EAB) of 3.52 GHz for the sample composed of 1T/2H mixed-phased structure.